Neuronal development and synapse formation will be examined in dissociated cell cultures prepared from embryonic chick tissue. The major cell type to be studied will be cholinergic neurons from spinal cord tissue and from ciliary ganglia. Skeletal myotubes will provide the postsynaptic target cells for the cholinergic neurons. Individual neuron cell types in heterogeneous cultures will be distinguished by electrophysiological methods and by autoradiographic labeling with neurotransmitter precursors. Neurotransmitter metabolism will be examined as a marker for the development of the presynaptic neurons. Electrophysiological techniques will be used to characterize functional synaptic transmission. The number and distribution of actylcholine receptors in the myotubes will be monitored to follow postsynaptic events during synapse formation. The correlation of these approaches should provide information about how synapses are formed between appropriate cell types.